Ring nebula and bipolar outflows associated with the B1.5 supergiant Sher 25 in NGC 3603

Wolfgang Brandner, Eva K. Grebel, You Hua Chu, Kerstin Weis

Research output: Contribution to journalArticle

Abstract

We have identified a ring-shaped emission-line nebula and a possible bipolar outflow centered on the B1.5 supergiant Sher 25 in the Galactic giant H II region NGC 3603 (distance 6 kpc). The clumpy ring around Sher 25 appears to be tilted by 64° against the plane of the sky. Its semimajor axis (position angle ≈165°) is 6″.9 long, which corresponds to a ring diameter of 0.4 pc. The bipolar outflow filaments, presumably located above and below the ring plane on either side of Sher 25, show a separation of ≈0.5 pc from the central star. High-resolution spectra show that the ring has a systemic velocity of VLSR = +19 km s-1 and a deprojected expansion velocity of 20 km s-1, and that one of the bipolar filaments has an outflow speed of ∼83 km s-1. The spectra also show a high [N II]/Hα ratio, suggestive of strong N enrichment. Sher 25 must be an evolved blue supergiant (BSG) past the red supergiant (RSG) stage. We find that the ratio of equatorial to polar mass-loss rate during the RSG phase was ≈16. We discuss the results in the framework of RSG-BSG wind evolutionary models. We compare Sher 25 to the progenitor of SN 1987A, which it resembles in many aspects.

Original languageEnglish (US)
Pages (from-to)L45-L48
JournalAstrophysical Journal
Volume475
Issue number1 PART II
StatePublished - Jan 1 1997

Keywords

  • ISM: individual (NGC 3603)
  • Stars: evolution
  • Stars: individual (Sher 25)
  • Stars: mass-loss
  • Supergiants
  • Supernovae: individual (SN 1987A)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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